The present invention relates to a process for producing neuraminidase. Neuraminidase (EC 3.2.1.18) is a hydrolase, of which substrate is a ketoside having an .alpha.-configuration in sialic acid residues (acyl derivatives of neuraminic acid are collectively called sialic acid) located at the ends of glycoproteins, glycolipids, etc., important constituents of the living body, and which is capable of releasing the sialic acid residues.
Neuraminidase is used for quantitative determination of sialic acid-containing substances in the living body, such as sera, etc., and utilized in the field of clinical diagnosis of various inflammatory diseases, diffuse collagen diseases, cancer, etc.
It is known that neuraminidase is widely distributed in microorganisms such as viruses, bacteria, actinomycetes, etc., various tissues from fowls, mammals, etc.
For the production of neuraminidase by using microorganisms, there have been known various processes wherein a microorganism capable of producing neuraminidase is cultured in a medium supplemented with a neuraminidase inducer such as colominic acid, a leach and extract of various animal tissues, and neuraminidase formed is recovered therefrom [Metabolism, 16 (5), 761 (1979); Biochim. Biophys. Acta, 350, 425-431 (1974); J. Biochem., 82, 1425-1433 (1977); J. Bacteriol., 119 (2), 394-400 (1974); Canadian J. Microbiology, 18, 1007 (1972); Japanese Published Examined Patent Application No. 11991/1975; and Japanese Published Unexamined Patent Application No. 34181/1985 (U.S. Pat. No. 4710470, EP 133694-A)].
It is extremely disadvantageous from an economical viewpoint to use neuraminidase inducers in large quantities upon production of neuraminidase. In order to produce neuraminidase at low costs in an industrial scale, it is necessary to use a microorganism which has excellent neuraminidase productivity and requires no neuraminidase inducer.